<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        .hehe{
            height: 100px;
            background: linear-gradient(to right,yellow,blue);
        }
    </style>
</head>
<body>
    <div class="hehe"></div>
</body>
</html>